1. Field of the Invention
The present invention relates to a zoom lens. Or, the present invention relates to an image pickup apparatus such as a digital camera and a video camera which includes the zoom lens.
2. Description of the Related Art
In recent years, electronic image pickup apparatuses such as a digital camera and a video camera in which, an arrangement is made to photograph an object by using not a film but an image pickup element such as a CCD (Charge Coupled Device) and a CMOS (Complementary Metal Oxide Semiconductor) sensor, have become mainstream.
The electronic image pickup apparatuses such as digital cameras of a high-function type for professional use, digital cameras of a portable popular type, and monitoring (security) cameras are in a widespread use.
In these electronic image pickup apparatuses, a zoom lens in which, it is possible to make a change in an angle of view of photography assuming various photographic scenes, has been preferred.
As a zoom lens which is advantageous for securing both a zoom ratio and a brightness at a telephoto end, a zoom lens having an arrangement of a plurality of lens units not less than four which includes in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a plurality of lens units has been known.
As a zoom lens which includes not less than four lens units in such manner, zoom lenses in Japanese Patent Application Laid-open Publication Nos. 2003-57544, 2005-316047, 2010-91881, and 2011-247949 have been known.